[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-3771) Best pactice for equals implementation?
Dmitry Katsubo (JIRA)
noreply at atlassian.com
Sat Jul 24 07:41:35 EDT 2010
[ http://opensource.atlassian.com/projects/hibernate/browse/HHH-3771?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=37908#action_37908 ]
Dmitry Katsubo commented on HHH-3771:
-------------------------------------
Why can't you first initialize collections using {{[Hibernate.initialize()|http://fisheye.jboss.org/browse/Hibernate/core/trunk/core/src/main/java/org/hibernate/Hibernate.java?r=HEAD#l387]}}, and then call {{equals()}}?
> Best pactice for equals implementation?
> ---------------------------------------
>
> Key: HHH-3771
> URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-3771
> Project: Hibernate Core
> Issue Type: New Feature
> Components: core, documentation
> Reporter: Samppa Saarela
>
> When domain model contains even one lazy reference to an object, default equals fails when it's compared to a) the actual implementation returned by Session.get/load or b) other proxies (at least of different supertype). Overriding equals on a class that uses surrogate id is not that simple. However there is a simple solution to this problem:
> In domain class, override equals like this:
> public boolean equals(Object obj) {
> return this == getImplementation(obj);
> }
> public static Object getImplementation(Object obj) {
> if (obj instanceof HibernateProxy) {
> return ((HibernateProxy) obj).getHibernateLazyInitializer().getImplementation();
> } else {
> return obj;
> }
> }
> This should result always in comparing object references of actual instances and thus preserve symmetry.
> It's understandable that you don't wan to publish that kind of getImplementation utility e.g. in Hibernate, but maybe you could support this more directly by implementing
> Hibernate.equals(Object o1, Object o2)
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